SR-MPLS – Static non-colored LSP
1. Intro The segment routing architecture enables the ingress devices in a core network to steer traffic through explicit paths. You can configure these paths using segment lists to define the paths that the incoming traffic should take. SR is a control-plane architecture that enables an ingress devices in a core network to steer traffic […]
SR-MPLS – Basic Config
1. Intro Segment Routing is also known as Source Packet Routing in Networking (SPRING), and it comes in two flavors SR-MPLS and SRv6 In a segment-routed network, source routing enables the first router in a path to calculate the end-to-end path. The source router can then write a series of MPLS labels or IPv6 addresses […]
RSVP – LDP Tunneling
1. Intro You can run LDP over LSPs established by RSVP, effectively tunneling the LDP-established LSP through the one established by RSVP. To do so: To demonstrate LDP tunneling we will use the following topology: As we see in the diagram, we have 2 LDP islands. Routers R1, R2, R3 and R4 have LDP configured […]
RSVP – install option
1. Intro By default, only /32 prefixes are installed in the inet.3 table. Using the install option, you can add additional prefixes to inet.3. By including the active parameter, the prefix is also added to the inet.0 table, which means that the IGP can also use this prefix. Remember that by default only BGP can […]
RSVP – OAM BFD
1. Intro We can configure OAM BFD for LSPs to detect LSP data plane faults. To bootstrap the OAM BFD session, there is an initial exchange of MPLS Ping packets (Echo Request/Reply) between the ingress and egress routers, that is using UDP port 3503. After the initial MPLS Ping exchange, the routers will exchange BFD […]
RSVP – soft-preemption/adaptive
1. Intro Essentially, we are discussing here about the make before break (MBB) feature. You will see MBB is enabled by default for some features, like periodic re-optimization of LSPs. By default, MBB is disabled for LSP preemption, but we can change this with either soft-preemption or adaptive. Soft preemption attempts to establish a new path for […]
RSVP – Link/Node Protection
1. Intro The Junos implementation of facility backup is link protection. This feature is interface based rather than LSP based. Whereas fast reroute is trying to protect the whole LSP (1:1 protection), link protection (1:n) protects only the link, however, it can protect multiple LSPs. A bypass LSP must terminate on the downstream LSR. Bypass […]
RSVP – fast reroute
1. Intro Fast reroute can dramatically reduce packet loss in the case a primary path fails. Even if you have a secondary path signaled with the standby feature there is still the possibility of many packet drops. This happens because the message for the failed path must still travel back towards the ingress LSR so […]
RSVP – Secondary Paths
1. Intro In the previous example we tested link coloring with multiple LSPs to the same destination, which is not ideal. In this post we will configure Secondary paths. By default, when network failures occur along the path of RSVP signaled LSPs, traffic will be dropped. The ingress LSR continues to send traffic until a […]
RSVP – Link Coloring
1. Intro Administrative groups provide the ability to mark the interfaces with similar characteristics in a common group. Based on these groups you can restrict the LSPs to use a certain path in the network. Marking the interfaces is known as coloring but is actually based on setting the affinity bits on interfaces. Up to […]